"Silkworms have changed their appearance" Animal life cycle PPT courseware 3

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"Silkworms have changed their appearance" Animal life cycle PPT courseware 3

Why does silkworm make a cocoon to wrap itself?

Because the pupa cannot move and has no ability to resist, if it is not wrapped up, it will be eaten by birds or other things, or it will be killed by the rain. To cover oneself is to protect oneself.

Pupa is another form of silkworm during its growth and development.

What is the difference between the appearance of pupae and silkworms:

The pupa body is short and short, spindle-shaped, divided into three parts: head, thorax and abdomen. The head is small, the body is shortened and dark brown.

The body of silkworm is long cylindrical, divided into three parts: head, chest and abdomen. The head is small and the body is bluish white.

The value of silkworm chrysalis

According to data, silkworm pupae are of relatively high value. my country began to cook and eat silkworm pupae more than 1,400 years ago. Silkworm chrysalis is rich in protein and a variety of amino acids. It is an advanced nutritional supplement for the frail, post-ill, elderly and postpartum women. Silkworm chrysalis can produce pharmacologically active substances, which can effectively increase the level of white blood cells in the human body, thereby improving the body's immune function and delaying the aging of human body functions. Silkworm chrysalis oil can lower blood lipids and cholesterol, and is significant in treating hypercholesterolemia and improving liver function. effect.

Observation records of pupae

1. What is the difference between the appearance of pupae and silkworms?

Silkworm pupae are stubby and spindle-shaped, while silkworms are long and cylindrical.

2. Can you still find the eyes and feet? Are the links on your body still there?

You can find the eyes and feet, and there are still links on the body.

3. Can pupae move? What's growing on it?

The pupa moves and has a scute on its back, from which two pairs of wings grow.

4. What else was found in the cut cocoon? What could it be?

There is also a layer of skin, which is the skin of the fifth molt of the silkworm.

Observe silkworm cocoon

1. Shape: oval

2. Color: Cocoons come in white, yellow, light green, flesh red and other colors. White cocoons are mostly used in production.

3. Size: The size of each cocoon is not exactly the same, about three to four centimeters.

Can you pull the silk out of the cocoon?

Soak the cocoon in hot water (dry silk breaks easily), use a bamboo skewer to pick out the silk ends, and wrap the silk around the cardboard to see how long the silk is.

silk

According to archaeological discoveries, China had used silk to make silk threads, weave ribbons and simple silk fabrics about 4,700 years ago.

Silk is light and slender, has good luster, is comfortable to wear, feels smooth and plump, has poor thermal conductivity, is moisture-absorbent and breathable. It is used to weave various satins and knitwear, and is used in fields such as industry, national defense and medicine. China, Japan, India, the former Soviet Union and North Korea are the main silk-producing countries, with total output accounting for more than 90% of world output.

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Update Time: 2024-09-16

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